Device for rolling teeth



, Jan. 14, 1958 G. w. LYMAN DEVICE FOR ROLLING TEETH Filed June 27, 1955 m mm M :M J n E, a mm m Wm m A 6 HQ United States Patent DEVICE FOR ROLLING TEETH George W. Lyman, Holden, Mass., assignor to Reed Rolled Thread Die Company, Holden, Mass, a corporation of Massachusetts Application June 27, 1955, Serial No. 517,992

3 filaims. (CI. 80-16) This invention relates to apparatus for forming teeth by a rolling operation, and more particularly to apparatus which will roll parallel teeth by a cold metal working operation.

It has been proposed to roll teeth on a round work piece by means of a plurality of freely rotatable die rolls having metal forming teeth arranged either parallel to the roll axis or diagonally parallel as required in a helical spur gear. The work is positively rotated and the die rolls are moved relatively along the work axis so as to roll a gear or spline which is longer than the width of the die rolls. Since the die rolls are freely rotatable, a problem is involved in matching the die rolls so that when the work initially engages them, the rolls will cooperate in producing the required results.

The primary object of this invention is to satisfy this requirement and to provide a construction which insures that the die rolls are held in a matched relationship when brought into engagementwith the work and which permits the work thereafter to maintain the required matching. Other objects will be apparent in the following disclosure.

Referring to the drawings:

Fig. l is a perspective view, partly broken away, showing one form of a thread rolling attachment for use on an automatic machine tool;

Fig. 2 is a longitudinal sectional view, with some parts in full and other parts broken away, which shows a positively rotated work piece in rolling contact with the dies and a movable gear unit in a matching mesh with the dies;

Fig. 3 is a fragmentary detail showing the work in rolling contact with the dies and the matching unit removed from the rolling zone; and

Fig. 4 is a fragmentary detail showing the adjustment for work size.

A metal rolling device embodying this invention comprises a set of freely rotatable die rolls having forming teeth thereon arranged parallel with the work axis. The die roll axes are fixed and the teeth so shaped as to form the work teeth by a progressive full depth penetration of work increments as the rolls are moved axially relative to the work. The die roll teeth are provided with tapered leading portions which engage the work gradually so that the portions of lesser diameter first engage the work with slight penetration, and as the work is moved axially, the tapered portion progressively penetrates to the full depth, after which the remaining tooth portion of uniform height serves to smooth and burnish the tooth thus formed. The die rolls are shown as shaped with serration adapted to form a splined shaft or other required shape. The die roll teeth are preferably parallel with the Work axis and thus can form Work teeth of extensive length only if the die rolls and the work are moved relatively in the direction of the work axis. This is provided by a positively acting slide or screw. The die rolls are each freely rotatable, and in order to insure a matching relationship at the beginning of the 2,819,632 Patented Jan. 14, 1958 work rolling operation, a supplemental gear shaped matching element is removably inserted between the dies to hold them matched until the newly formed work teeth can assume this function.

The construction illustrated is an attachment to be mounted on an automatic machine tool which has means for positively rotating a round work piece and for axially moving a plurality of freely rotatable die rolls in the required spaced arrangement to roll teeth on the work piece therebetween. A set of die rolls 20 are provided with substantially triangular teeth 21 shaped to form splines on a work piece W, as well as various other tooth shapes, such as axially parallel spur gear teeth and diagonally parallel helical spur gear teeth. Each die roll, as shown in Fig. 2, has tapered starts 22 on the leading ends of its teeth; and this taper may be provided at both ends of the die roll so that the latter may be reversed in position to lengthen its life. The die rolls, preferably three in number, are mounted for free rotation on the cylindrical surfaces of axles 24 carried by two spaced circular disks or plates 25 and 26. The reduced pivot ends 27 of each axle 24 are eccentric to the roll axis. These pivots 27 are rotatably mounted in the two plates 25 and 26 and arranged for a rotation to move the axles towards and from the Work axis to adjust for work size. This adjustment is accomplished by means of a gear system.

To this end, the rear plate 25 is mounted in a circular recess 30 in a circular supporting annular plate 31. The plate 31 has a set of symmetrically arranged elongated arcuate slots 34, and bolts 36 between the dies pass through the plates 25 and 26 and through the slots. A head 38 on the rear of each bolt and an adjustable nut 39 at the front serve to draw the plates tightly together and as positioned by a spacing sleeve 41 carried by each bolt. The outer plate 26 is supported solely by the three bolts 36. The two plates 25 and 26 may be rotated as a unit to the extent permitted by the arcuate slots 34. This rotation is employed to adjust the die rolls axially.

The rear end 27 of each axle 24 is shown as slightly reduced in size and provided with a gear 42 fixed thereon. Each of these gear 42 meshes with the teeth of a stationary gear 43 on a flange forming an end of the hub or mount 44 which terminates in a tubular extension 45 axially parallel with the work positioned between the die rolls. The plate 31 may be integral with the hub 44, but it is shown as a separate element mounted on a circular portion of the hub 44. It is clamped in position by means of locking nuts 46 threaded on a reduced portion of the hub 44. These lock nuts serve to hold the plate 31 stationary relative to the central gear 43. The small gears 42 on the ends of the roll shafts are mounted in an annular recess formed between the hub and its stationary gear 43 and the outer portion of the plate 31. If the two plates 25 and 26, which carry the die rolls, are rotated about the work axis to the slight extent permitted by the arcuate slots 34, this causes the gears 42 to roll about the stationary central gear 43 and thus to turn the die roll bearing mounts 24 and move the axis of each die roll radially in or out relative to the work. This adjusts the positions of the die rolls to provide the required work size and depth of rolled tooth.

The tubular member 45 serves as a post which is adapted to be clamped on a suitable support on the machine tool in such a position that the die rolls 20 surround and engage the work. After their radial adjustment, the die roll axes are fixed relative to the work with a correct spacing which insures that the work is progressively shaped by a full depth increment penetration to form the required parallel splines or teeth. The post 45 is hollow and extensive in length and so arranged that it not only supports the die rolls but permits the work to pass into or through the inner cylindrical bore therein as the splines or teeth are rolled progressively.

Matching of the die rolls is insured by a supplemental gear type of matching element 59 which has splines or teeth on its surface so shaped that the matching element meshes accurately with the die rolls and holds them in a required relationship. in the construction illus trated, the various parts are so arranged as to form only a short splined end on the cylindrical work piece, and in that case the matching gear element may be so mount ed that it may be moved only through a short distance to permit passage of the work to the required extent. The element 50 is mounted on the end of a spindle 52 carried in .ball bearings 53 of standard construction. The bearings are mounted within a cylindrical sleeve 55 which slides within the cylindrical interior of the post 45. Nuts 57 on a reduced threaded end 58 of the spindle 52 clamp anenlarged flange 59 of the spindle 5'2 against the inner ball bearing ra-ceways 53 and thus hold the matching element 5% in a proper rotative position. A helical compression spring 6t) held in place by a cap screw 62 in the threaded end of the post 45 is compressed between that cap screw 62 and the end of the slidable sleeve 55 which carries the matching element spindle 52. This serves to thrust the matching element into position between the die rolls, this movement being limited by the flange 59 engaging the sides of the die rolls, or otherwise as desired. The element Bil has its leading end as tapered, as shown in Fig. 3, so that it may be readily moved by the compressed spring into a matching relationship with the die rolls 20. As the work is thrust through the rolling zone, it pushes the element 50 toward the left against the compressive force of spring 6t) and moves the element 50 out of the way. That is to say, this element serves as a gear which meshes accurately wth the die rolls and holds them matched until the work piece moves forward and the newly formed splines on the work take over the duty of holding the die rolls in a matched relationship. For a longer work piece, the spring 60 may be replaced by other suitable mechanism, such as a pneumatically operated piston, which will normally urge the element 50 into a matching relationship but will yield as the work travels forward, or the element 55d may be manually inserted be tween the die rolls and then be pushed out of the tube 45 by the work. Thus, the work which passes through the large central holes in the plates 25, 26 and 31, may have splines or other forms of teeth rolled thereon by the die rolls, and the latter are always matched.

The full depth penetration of the die roll teeth into the work involves a. high force, and to move the work axially, the work may be mounted on a screw operated machine tool bed which may be manually or mechanically fed forward to move the work, or a fluid pressure plunger mechanism of suitable construction may be employed for the purpose.

Fig. 2 includes a diagrammatic showing of a screw feed mechanism for moving the dies axially and a positively driven dog for rotating the work. As there shown, the work W is suitably mounted in a chuck of standard construction which may comprise three separate jaws clamped against the outer periphery of the work by means of a tapered collar 71. The chuck is mounted in a bearing 72 carried on the machine base 73 and the dies are slidably supported on a slide 75 carried by the bed 74 of the machine tool. A screw 76 suitably mounted on the machine bed is mechanically driven, as by a gear mechanism, to feed the slide 75 positively forward and force the rolls along the work. It will be appreciated that many types of machine tool may be used for this purpose and that modifications may be made therein to accomplish the work-feeding operation. Either the work or the rolls may be moved axially and the die head may be rotated about a stationary work and driven by a suitable mechanism,

such as a chuck. The rotation of the work is indicated diagrammatically as comprising a pulley 78 directly connected to the shaft carrying the chuck. In either construction, the work piece W is relatively rotated in rolling association with the die rolls 20 while one of the parts is moved axially by a pressure mechanism, such as a screw or a fluid pressure actuated plunger. Since the die rolls are freely rotatable, they are brought into a matching relationship as above explained by means of the gear element 50 and this element is moved out of the rolling zone as the work takes over the function of matching the die rolls. It will be understood that the teeth of the die rolls are to be considered as parallel whether arranged parallel to the axis as illustrated or diagonally relative to the die roll circumference as is required for rolling helical spur gear teeth. Also, the die roll teeth are suitably shaped to roll splines, involute gear teeth and other forms. The macthing element will mesh with the die rolls for slight radial adjustments thereof, or the matching element may be replaced by one of a desired size.

It will now be appreciated that various modifications may be made in this construction, and that the disclosure of the principles and a preferred embodiment are not to be interpreted as limiting the appended claims.

What is claimed is:

1. A device for rolling teeth on a round work piece comprising a plurality of freely rotatable die rolls having work rolling teeth thereon, means for supporting the rolls for free rotation relative to a work piece therebetween, mechanism for positively rotating only the work, means for relatively moving the work and die rolls axially to move the work through the rolling zone, a freely rotatable matching element having teeth thereon adapted to interfit with the die roll teeth and hold the die rolls in a matching relationship and means for positioning the element initially in a matching relationship with the die rolls, which provides for said element being removable from the work rolling zone by the relative axial movement of the work and die rolls as teeth are progressively formed on the work and assume the function of die roll matching.

2. Apparatus for rolling teeth on a round work piece comprising a set of freely rotatable die rolls having parallel work rolling teeth thereon, means for mounting the rolls for engagement with a work piece rotatably supported in die rolling contact therewith, means for positively rotating only the work, means for causing the work and die rolls to move relatively axially of the work so that the rolls may be rotated by the work and teeth may be rolled progressively on the work in small increments of full depth penetration, a freely rotatable matching element having teeth capable of meshing with the die roll teeth, and yielding means. for urging the element into a matching relationship with the die rolls, the relative axial movement of the work and die rolls serving to move the element out of its matching relationship with the rolls as the latter progressively engage and roll the work and the newly formed teeth on the work assume the matching function.

3. A tooth rolling device according to claim 2 comprising a tube fixed axially of the work, a slide in said tube, hearings in the slide rotatably supporting the tooth matching element and means for urging the slide and element toward the work rolling zone which yields as the work is moved progressively therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 1,883,080 Stull et al. Oct. 18, 1932 1,923,477 Coda Aug. 22, 1933 FOREIGN PATENTS 9,787 Great Britain May 5, 1908 

